Products useful for determining or monitoring the condition of productive assets, including but not limited to equipment and processes, most often perform this surveillance function by evaluating signal or data values obtained during asset operation. One means for determining or monitoring the condition of an asset involves estimating the expected data values and comparing the estimated values to current data values obtained from the asset. When the estimated data values characterize the desired or expected operation of the asset, a disagreement between the estimated data values and the current data values provides a sensitive and reliable indication of an asset fault condition and can further provide an indication of the particular cause of the asset fault. The disagreement between each estimated data value and each current data value can be computed as the numerical difference between them. This difference is often referred to as a residual data value. The residual data values, the current data values, or the estimated data values can be used to determine condition of the asset and to identify asset faults. We will hence forth refer to techniques used to identify asset faults as fault detectors.
Assets age with time. The current data values, estimated data values, and residual data values often change over time as the result of asset aging. Unfortunately, typical fault detectors used today are static and do not adjust or recalibrate automatically over the life cycle of the asset. This can result in false alarms using static fault detectors as the asset ages. To prevent such false alarms, it is often necessary to reduce the sensitivity of the fault detector to accommodate the aging behavior of the asset. Unfortunately, this results in increased numbers of missed alarms during slow failure of the asset and delays fault identification and correction.
In the alternative, the operators of the asset might manually recalibrate the fault detectors periodically to maintain adequate sensitivity. This is undesirable since manual recalibration of fault detectors might not be practical for assets deployed in-service. For most types of fault detectors, manual recalibration might additionally require temporary suspension of the asset monitoring process.
For the foregoing reasons, there is a need for an asset surveillance system and method that overcomes the significant shortcomings of the known prior-art as delineated hereinabove.